BAG3 promotes autophagy and suppresses NLRP3 inflammasome activation in Parkinson's disease

Background: Neuroinflammation mediated by microglia plays a key role in the pathogenesis of Parkinson's disease (PD), and our previous studies showed this was significantly inhibited by enhanced Autophagy. In the Autophagy pathway, Bcl2-associated athanogene (BAG)3 is a prominent co-chaperone, and we have shown BAG3 can regulate Autophagy to clear the PD pathogenic protein α-synuclein. However, the connection between BAG3 and microglia mediated neuroinflammation is not clear.

Methods: In this study, we explored whether BAG3 regulated related neuroinflammation and its original mechanism in PD. An inflammatory model of PD was established by injecting adeno-associated virus (AAV)-BAG3 into the bilateral striatum of C57BL/6 male mice to induce overexpression of BAG3, followed by injection of lipopolysaccharide (LPS). The striatum was extracted at 3 days after injection of LPS for Western blotting and reverse transcription quantitative polymerase chain reaction (RT-qPCR), and immunohistochemical staining was performed at 21 days after injection. At the same time, LPS was used to induce activation of BV2 cells to verify the effect of BAG3 in vitro.

Results: Overexpression of BAG3 reduced LPS-induced Pyroptosis by reducing activation of Caspase-1, the NOD-like receptor family, and the pyrin domain-containing 3 (NLRP3) inflammasome, and by release of interleukin (IL)-1β and tumor necrosis factor (TNF)-α. The LPS-induced inflammatory environment inhibits Autophagy, and overexpression of BAG3 can restore Autophagy, which may be the mechanism by which BAG3 reduces neuronal inflammation in PD.

Conclusions: Our results demonstrate BAG3 promotes Autophagy and suppresses NLRP3 inflammasome formation in PD.

Bcl2-associated athanogene 3 (BAG3); NOD-like receptor family, and the pyrin domain-containing 3 inflammasome (NLRP3 inflammasome); Parkinson’s disease (PD); autophagy; microglia.